Description Chomerics’ family of thin heat spreaders provides a low-cost, effective means of cooling IC devices in restricted spaces where conventional heat sinks are inappropriate. T-Wing spreaders consist of 5oz. (0.007inch/0.18mm thick) flexible copper foil between electrically insulating films. High strength silicone PSA (pressure-sensitive adhesive) provides a strong bond to the component. The compliant nature of these “thermal wing” heat spreaders permits nearly 100% adhesive contact with non-flat package surfaces, optimizing thermal and mechanical performance.
Features/Benefits
• Component junction temperature reduction of 10-20°C is common • Easily added to existing designs to lower component temperatures and improve reliability
• Custom shapes available for complex designs
Typical Applications
• Microprocessors
• Memory modules
• Laptop PCs and other high density, handheld portable electronics • High speed disk drives
Design Details
• Low profile (0.33mm/0.013in) allows use in limited space environments
• Easy peel and stick adhesion to all surfaces, including packages with residual silicone mold release
• Offers low cost cooling for many package types
• Low application force
(<5psi/ 0.03MPa) minimizes risk of damage to component
• Available in a range of standard sizes
• Pliable nature allows conformance to concave or otherwise non-flat surfaces for optimal thermal and mechanical performance
• Light weight (0.039 oz/inch2)
• Standard parts are scored for easy forming and alignment
• Easy removal for device replacement
• Available die-cut on continuous rolls


T-Wing® Heat Spreaders
Testing Summary
Summaries of test procedures used for T-Wing heat spreaders are described below. Thermal performance, adhesion strength and visual inspection were used as pass/fail criteria.

Apparatus
Anatek® Thermal Analyzer: The ATA was used to measure Rj-a before and after environmental stressing. PQFP: 196 lead, plastic PQFPs known to contain silicone mold release were evaluated. T-Wing Heat Spreader: 1 inch x 4 inch TWing parts were applied to the PQFP packages with a 5 psi (0.03 MPa) mounting pressure.


Thermal Performance
Various sizes of T-Wing heat spreaders were applied to a 196 lead PQFP using less than 5 psi (0.03 MPa) bonding pressure. Within 30 minutes of application, the test boards were mounted in an Analysis Tech® thermal analyzer. The devices were heated to equilibrium (45 to 60 minutes) with approximately 3 watt load on 3 x 3 inch (7.6 x 7.6 cm) test boards. Two test environments were used: restricted convention, achieved with a 1 x 5 x 6 inch (2.5 x 12.7 x 15.2 cm) plexiglass box; and 100 LFM (30m/min) air flow. Results were obtained using thermocouples for Tc (centered on case) and Rj-a.


Environmental Stressing
Control: Specimens were maintained for 1000 hours at standard laboratory conditions, 23°C, 35-60% RH.

Heat Aging: Test specimens were placed in a forced convection hot air oven maintained at 150°C ±5°C for 1000 hours. Test specimens were then removed and tested.

ElevatedTemperature/HighHumidity: Specimens were placed in a humidity chamber maintained at 85°C ±2°C and 90%-0 +10% RH for 1000 hours.

Temperature Cycling: Specimens were subjected to 500 cycles from -50°C
to +150°C in a Tenney Temperature Cycling Oven.

Temperature Shock: Specimens were subjected to 100 temperature shocks by immersion into -50° and +150°C liquids. Temperatures were monitored with thermocouples.


Evaluation Procedure

Visual: All test specimens were exam- ined for de-bonding, delamination or other signs that the tape was failing after environmental stress.

Thermal Performance: T-Wing was applied to the PQFP with 5 psi mount- ing pressure. After a one hour dwell, the Rj-a of each specimen was mea- sured at 100 LFM and under restricted convection conditions. The Rj-a was again measured after environmental stressing.

90° Peel Strength: A T-Wing heat spreader was applied to each PQFP with 5 psi mounting pressure. The specimens were subjected to environ- mental stress and then tested for 90° peel strength at room temperature.